Field of the Invention
This invention relates to a rotary position detector, more particularly to techniques of detecting a rotary position which indicates a revolution number of a rotator rotatable in a plurality of times, and further, relates to a rotary position detector effective, for example, for being utilized in detecting a revolution number of an output shaft of a sun-roof driving device mounted onto a motor vehicle.
In order to automatically operate the sun-roof driving device mounted onto the motor vehicle, it is necessary to detect a number of revolution of an output shaft from a home position thereof.
As a rotary position detector for detecting the revolution number of the output shaft of the sun-roof driving device, such an arrangement has heretofore been adopted that a cam is operationally associated with the output shaft through an intermittent operation mechanism or a reduction mechanism, a plurality of limit switches are arranged at an interval around the cam in the circumferential direction,.positions of the cam in one rotation are detected by the respective limit switches, so that the revolution number of the output shaft having rotated a plurality of times can be detected.
However, with the above-described rotary position detector, the intermittent operation mechanism or the reduction mechanism for greatly reducing the plurality of rotation of the output shaft to one rotation involves a complicated construction, and further, use of the plurality of limit switches of high price leads to increase in cost.